An improved strip-line fast Faraday cup for beam bunch measurements

A 3 MeV proton radio frequency quadrupole (RFQ) accelerator has been designed, built, and commissioned at the Bhabha Atomic Research Centre, India. A compact wide bandwidth strip-line fast Faraday cup (SFFC) has been developed for the beam bunch measurements of the 352 MHz RFQ. The SFFC design is improvised over the standard strip-line FFC designs with a thicker strip, which can withstand larger beam intensities. The absence of the pinhole beam limiting aperture and the provision for a suppressor electrode to suppress secondary electrons on the strip are other improvisations over standard SFFC designs. The SFFC has been characterized using the time domain reflectometry method, and a broad bandwidth of ∼7 GHz is measured. The SFFC has been tested with a 3 MeV RFQ beam at a 4 mA peak current. The time structure of the individual micro-pulses with a FWHM of 297 ps has been measured with a SFFC.